By Daniel Denvir

Philadelphia school officials are hungry for data. The district's new safety chief plans to use CompStat, a statistical crime-fighting tool employed by police here and elsewhere. It provides data that could be useful, say, in uncovering a pattern of racially motivated violence at a school.

But in police precincts as well as classrooms, numbers can take on lives of their own. Much like "friends" on Facebook, statistics can become substitutes for experience.

In the HBO series The Wire's insightful dramatization of the CompStat approach, an anxious mayor demands results from a police chief, who in turn uses high-pressure meetings to rake commanding officers over the coals for failing to meet crime-reduction targets. The commanders then direct their officers to work on getting this or that number down - to the detriment of good police work.

In the real world, the drive to get the numbers right has led to spectacular abuses in the New York Police Department's 81st Precinct, in Brooklyn, as uncovered by the Village Voice. Officers arrested people for small crimes or less, while discouraging victims of serious crimes from pursuing justice. Detectives in Manhattan were unaware that a serial rapist was at large because reports had been downgraded to misdemeanors.

The same misuse of numbers already afflicts our public schools thanks to ever more high-stakes standardized tests. Scandals over manipulated scores have sprouted up around the country, most recently in Atlanta, and dramatic gains on state exams are often contradicted by national assessments. The data-mania is reaching a fever pitch.

The Los Angeles Times recently published a districtwide analysis of every educator's "value-added" effectiveness in raising student test scores - with the teachers' names attached. This was public humiliation dictated by a higher computational power.

The Obama administration's Race to the Top initiative puts a premium on tying teacher evaluation, compensation, and discipline to students' test scores. And at schools throughout Philadelphia, students gather for rallies to pump them up for making "AYP" (adequate yearly progress) on standardized tests - as though knowledge could be enhanced through sheer enthusiasm.

Test-based accountability has made school more boring - at worst, a long-form Kaplan test prep seminar. No time for civics, history, or art: Why study what's not being tested?

Schools that don't succeed are closed or converted into privately managed charters. (We could hang a similar threat over the heads of the nation's police departments, handing "failing" forces over to private security firms like Blackwater.) And private-sector management gurus preach the gospel of efficiency to incorrigible teachers; forget about treating and paying them like professionals.

In this way, numbers can supplant the all-important things - such as crime levels and educational attainment - they were supposed to measure, becoming ends in and of themselves. Statistics dressed up as solutions prevent us from doing the hard math.

Daniel Denvir is a Philadelphia journalist. He can be reached at